Wednesday, January 28, 2009

Considering they can't wield a knife or cleaver, dolphins make impressive butchers. Researchers in Australia recently observed a bottlenose performing a precise series of manoeuvres to kill, gut and bone a cuttlefish.

The six-step procedure gets rid of the invertebrate's unappetising ink and hard-to-swallow cuttlebone.

The procedure begins when the dolphin shoos a cuttlefish out of an algal forest into an open patch of the seabed. Next, she pins the cuttlefish down, ramming it into the ground. To rid the body of ink, she uses her snout to pick up the cuttlefish, and then shakes it several times until a black cloud streams out.

Let's walk through that again:

The dolphin begins the routine by shooing a cuttlefish out of hiding

She proceeds to pin it to the sand to kill it

Next, she nudges the invertebrate off the seafloor with her snoutTo remove the cuttlefish's ink, which can slow digestion, the dolphin shakes it back and forth

Rubbing the inkless corpse against the sand breaks and releases its indigestible cuttlebone

Men may be intrigued to hear that researchers have pinpointed a gene that makes females suck up sperm through their mouths.

The gene was found in the cichlid fish, where the males have evolved a way to lure females close so that they can squirt sperm into their mouths.

As is the case in many fish species, the sight of a brightly coloured male somehow triggers females with ripe eggs to start releasing them. But in cichlids, there is a twist. Females hold their eggs in their mouths and incubate them there after fertilisation - a behaviour that is thought to have evolved to protect the eggs from predators.

As soon as a female has spawned her eggs, she collects them up in her mouth. Normally, sperm released into the water by a male nearby will then fertilise the eggs.

But males of certain cichlid species in east Africa have evolved a way to increase the odds that females take up their sperm. Oval yellow markings resembling the eggs are found on the anal or pelvic fins. When a female approaches the male, she thinks she sees an egg on its fin, so tries to vacuum it up in her mouth - and get a mouthful of sperm from the canny male in the process.

'Turned on'

Salzburger's team believes it has now identified the gene that makes this bizarre mating behaviour possible.

They suspected a gene called csf1ra - short for colony-stimulating factor 1 receptor a, was responsible - because they knew that zebrafish lacking this gene failed to produce a yellow pigment similar to the shade of the cichlid fin spots.

The researchers extracted DNA samples from 19 cichlid species - nine that had egg spots on their fins and 10 that did not. They found the species that had evolved most recently had a mutation in the csf1ra linked to the egg spots.

Salzburger says this shows that the dummy egg spots are a genetic trait that provides a selective advantage because they encourage females to participate in oral mating.

Friday, January 2, 2009

This Coleopteran is named the golden tortoise beetle because of the resemblance the "shelf" that skirts the outside of the wings and thorax bares to a tortoise. These critters are able to alter their vibrant color within a short time period, turning from brilliant gold to a dull, spotty reddish color. When disturbed, they become orange with black spots. Pretty ferocious.

About Me

"We need another and a wiser and perhaps a more mystical concept of animals. Remote from universal nature, and living by complicated artifice, man in civilization surveys the creature through the glass of his knowledge and sees thereby a feather magnified and the whole image in distortion. We patronize them for their incompleteness, for their tragic fate of having taken form so far below ourselves. And therein we err, and greatly err. For the animal shall not be measured by man. In a world older and more complete than ours, they move finished and complete, gifted with extensions of the senses we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings; they are other nations, caught with ourselves in the net of life, fellow prisoners of the splendor and travail of the earth."
--Henry Beston, 1928